John Wesley Judd (1840–1916) had a distinguished career, serving as both President of the Geological Society and Dean of the Royal College of Science. Before his retirement as Professor of Geology from Imperial College, he wrote this concise and accessible review of the beginnings of evolutionary theory. Judd skilfully examined the roots of an idea that, already by 1910, had profoundly influenced every branch of science and permeated the work of historians, politicians and theologians. His lively narrative introduces the key individuals, including Darwin and Lyell, who brought about this intellectual revolution. Judd analyses the principal influences that worked upon these scientists as well as the factors that permitted them to remain open to radical new views. His appreciation of the vision, courage and far-reaching impact of the work of both Lyell and Darwin, and the interplay between their ideas, is persuasively and eloquently expressed.